Sputtering apparatus using passive arc control system and method

ABSTRACT

An arc control system includes a sputtering chamber that houses an anode and a sputtering target formed from a target material and serving as a cathode. A DC power supply provides a DC voltage between the cathode and anode such that a cathode current flows from the anode to the cathode. A resonant network is coupled between the DC power supply and the chamber. The resonant network has sufficient Q so that in reaction to an arc, the cathode current resonates through zero, causing a positive voltage to be applied between the cathode and anode. A reverse voltage clamp is coupled across the resonant network to clamp the cathode voltage to a predetermined reverse voltage. The reverse cathode voltage inhibits subsequent arcing by positively charging insulated deposits on the sputtering target. The arc control system limits the quantity of energy that is dissipated by the arc.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates generally to plasma-based thin filmprocessing. More particularly, the invention relates to an arc controlapparatus for DC sputtering systems that decreases the recovery timefrom an arc.

With the increasing demand for optical and disk media such as CD, DVD,MD, MO, DLC films, and hard disks; the importance of the sputteringprocesses that are used in the manufacture of these media continues toincrease. There are numerous types of sputtering systems, all of whichare employed to deposit insulating or conductive coatings on devicesranging from semiconductors to drill bits. The films that are generallyapplied to optical and disk media are typically created with asputtering process having poor control over the sputtering gas, i.e. asignificant fraction of atmosphere and petrochemical volatilities are inthe chamber at the beginning of the process.

During the initial sputtering phase, atmosphere is introduced into theplasma chamber to combine with freed target material. The resultingcompound, typically oxides and nitrides, may form a film on the surfaceof the target. This is referred to as target poisoning, and will causearcing in DC sputtering. Arcing, though inevitable in these processes isa mixed blessing. The arc often removes the poisoning from the target,but it may also generate undesirable particles to damage the substrateor disk.

Further sources of arcing include contaminants such as moisture,atmospheric gases, inclusions, and outgassing from the workpiece mayalso cause arcing.

In addition to particulate defects, arcing may lead to a defect commonlyknown as “mousebites”, which is illustrated in FIG. 1. A mousebite 9 isan irregularity that generally occurs along the edges of a workpiececoating. The occurrence of mousebites is related to the configuration ofthe power supply and attached energy storage components. In applicationssuch as coating CDs, the effect of mousebites can be attenuated byincreasing the portion of the workpiece adjacent to the edges that ismasked from coating. However, masking limits the usable area of theworkpiece, thereby increasing the need for maintenance, i.e. replacementof the mask due to coating buildup.

To control arcs, conventional DC sputtering systems include arcsuppression systems that are either attached to or integrated into thepower supply. Arc suppression systems may be divided into two groups.The first type, periodic arc control systems, cause a periodicallyoccurring interruption or voltage reversal of the cathode voltage in anattempt to avoid arcing. The second type, arc initiated control systems,bring about an interruption only after the beginning of an arc has beendetected.

Periodic suppression systems universally employ at least one activeswitch (in shunt or series to the cathode) to interrupt the flow ofcurrent or to apply a reverse voltage to the cathode. The frequency andpulse width of the switch are normally set so that arcing is suppressed,thereby eliminating defects that result from target poisoning and itsassociated arcs. A disadvantage of periodically interrupting the cathodevoltage is that the basic deposition rate may be reduced since thecathode voltage is not continuously applied. Another disadvantage ofperiodic suppression systems is the additional cost of the activedevices and associated control circuits. Generally, periodic suppressionsystems are only employed when defect free deposition is required, suchas in the manufacture of semiconductors.

Arc initiated control is employed for the manufacture of devices inwhich lower cost and reduced deposition times are the primaryrequirements. Traditionally, an arc initiated control system senses theinitiation of an arc, and in response disables the power supply drivingthe cathode. Generally, these control systems permit a significantquantity of energy to be dissipated in the arc before disabling thepower applied to the cathode. The quantity of energy dissipated in thearc is also dependent on the type of power supply to which the arcinitiated control system is attached. Since arc control systems do notcompletely prevent arcing like periodic suppression systems, but insteadact in response to the detection of an arc, particulate defects tovarying degrees will occur. In addition, with some combinations of powersupplies and arc initiated control systems, mousebite defects may alsooccur. In addition, deposition times may also be adversely affected,since while an arc occurs there is no deposition on the substrate.

While the prior art can be used to provide a DC sputtering system, ithas not proven capable of providing low cost arc control that does notadversely affect the deposition time or the quality of the coating.Accordingly, it is desirable to provide a low defect arc control systemthat does not compromise the deposition rate of the process. Inaddition, eliminating defects from the workpiece is desirable. Also, itis desirable to reduce deposition defects caused by target poisoning.

The present arc control system and method provide a system forcontrolling an arc. The arc control system includes a sputtering chamberthat houses an anode and a sputtering target formed from a targetmaterial and serving as a cathode. A DC power supply provides a DCcathode voltage such that a cathode current flows from the anode to thecathode. A resonant network is coupled between the DC power supply andthe chamber. The resonant network has sufficient Q so that in reactionto the occurrence of an arc, the cathode current resonates to a negativevalue as is well known in the art. A reverse voltage clamp is coupledacross the resonant network to clamp the cathode voltage to apredetermined reverse voltage value, and allow the negative portion ofthe resonant waveform to drive the cathode and reverse charge the targetsurface. Thus reverse current of the network is allowed to flowunimpeded to the cathode. This reverse current then charges the cathodeto a clamped positive voltage.

For a more complete understanding of the invention, its objects andadvantages, reference may be had to the following specification and tothe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary workpiece having mousebites;

FIG. 2 is a block diagram of a sputtering system constructed inaccordance with the teachings of the invention;

FIG. 3 is a schematic diagram of a presently preferred embodiment of theinvention;

FIG. 3A is a schematic diagram of a voltage clamp;

FIG. 3B is a schematic diagram of another voltage clamp;

FIG. 4A illustrates a sputtering system during a voltage reversal;

FIG. 4B illustrates a conventional sputtering system during a voltagereversal;

FIG. 4C illustrates a sputtering system in accordance with theprinciples of the present invention during a voltage reversal; and

FIG. 5 is a signal diagram showing the cathode current and voltagewaveforms associated with an arc.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 2, a DC sputtering system 10 according to the presentinvention is shown. In the presently preferred embodiment of theinvention, the DC sputtering system 10 uses a DC sputtering process todeposit a coating on a workpiece 16. Although, the workpiece in thepresent embodiment is an optical disk storage media such as CDs andDVDs, it is within the scope of the invention to coat other items suchas drill bits, glass panels, toys, cutting tools, optical equipment forany substrate, or a sputtered thin film. This process is unusual in thatthere typically is about 50 percent atmosphere in the sputtering chamberat the beginning of the deposition process. The oxygen and nitrogen ofthe air may convert some aluminum deposition to a Al₂O₃ and AINdeposition for the first part of the run. During the early portion ofthis process, arcing may occur due to outgassing, atmospherecontamination, etc.

The sputtering system 10 includes a sputtering chamber 12 that providesa controlled environment for the deposition process. A vacuum pump 11 istypically used to maintain the sputtering chamber 12 at a controlledpressure. The workpiece 16 may be a CD, DVD, cuTfing blade, or otheritem to be coated. A sputtering target 18, configured as a cathode,serves as a source of material for the coating. In the presentlypreferred embodiment the target 18 is formed from aluminum, althoughother suitable materials and alloys such as Gold, Si, Ta, B, and Ti maybe used. Another piece of conductive material within the sputteringchamber 12 serves as an anode 20. The cathode 18 and anode 20 arecoupled to a DC power supply 24 which supplies electrical energy forinducing a plasma within the sputtering chamber 12. In the presentlypreferred embodiment the atmospheric gas introduced at the start of theprocess is a contaminant. A controlled amount of a sputtering gas, forproviding anions that flow within the plasma, is also supplied to thesputtering chamber 12. Typically argon or another noble gas is used asthe sputtering gas.

For this particular application of the invention, wherein an opticaldisk is coated, a pair of shields are included in the chamber 12 formasking the outer and inner edges of the optical disk that is used asthe workpiece 16. The shields provide well defined outer and inner radiifor the optical disk. An outer shield 14 is positioned between thetarget material 18 and the optical disk 16 to prevent the deposition ofcoating material on the outer edge. An inner shield 17 is likewisepositioned to prevent coating of the inner edge of the optical disk.

The DC power supply 24 provides electrical energy for the sputteringprocess. The power supply 24 converts unregulated AC line power toregulated DC power suitable for powering the sputtering system 10. Inthe presently preferred embodiment of the invention, the DC power supply24 is a switch mode power supply, however, the scope of the invention isnot limited by the type of power supply. For example, other types ofpower supplies such as SCR and diode-transformer power supplies may beused. The positive 26 and negative 28 outputs of the DC power supply 24are coupled to the anode 20 and cathode 18, respectively. The powersupply 24 provides the required voltage/current to the sputteringchamber 12. As will be recognized by those skilled in the art, thenominal voltage is to be suitable for the target material and sputteringoperation to be performed. Therefore, the scope of the inventionincludes sputtering processes employing a wide range of voltages. Aresonant network 30 and voltage clamp 32 are connected between the DCpower supply 24 and the cathode 18 and anode 20. The resonant network 30stores electrical energy that drives a voltage reversal at the cathode18 and anode 20 during an arc event. Although, the resonant network 30is illustrated as being separate from the power supply 24, it is withinthe scope of the invention to integrate the resonant network 30 into thepower supply 24. Indeed, as will be subsequently explained, theperformance of the resonant network 30 is correlated to the outputfilter of power supply 24. The voltage clamp 32 limits the amplitude ofthe voltage reversal that is applied across the cathode 18 and anode 20during an arc and may additionally be configured to clamp excess normalvoltages to protect the power supply 24 and the workpieces 16.

Referring to FIG. 3, a partial electrical schematic of the presentlypreferred embodiment of the sputtering system 10 is illustrated. The DCpower supply 24 includes, in addition to other elements, an outputfilter 33 that comprises an output inductor 34 and an output capacitor36. Those skilled in the art will recognize that there are multipleoutput filter configurations that will operate with the claimedinvention. For example, multiple stage filters, damped output filters,and high impedance output filters are all within the scope of theinvention.

The resonant network 30 is configured to store energy during normalsystem 10 operation. The stored energy is subsequently released to thesputtering chamber 12 during an arc occurrence to enhance the systemresponse. A resonant capacitor 38 is connected across the positive andnegative outputs 26 and 28 of the DC power supply 24. In the presentlypreferred embodiment, a 0.1 μF polypropylene film capacitor is used forthe resonant capacitor 38, although many values may be used dependent onthe output design of the power supply 24 and magnetron cathode 18. Aresonant inductor 40 is connected from the resonant capacitor 38 tovoltage clamp 32. The resonant inductor 40 stores energy to be used inresponse to an arc, and also limits the rate of increase in outputcurrent during an arc. In the presently preferred embodiment, theresonant inductor 40 is 12 μH, though other values may be used.

The voltage clamp 32 limits the amplitude of the voltage applied to thesputtering chamber 12. The voltage clamp 32 includes a reverse voltageclamping device 44 connected from cathode 18 to anode 20. The reversevoltage clamping device 44 limits the reverse voltage applied to thesputtering chamber 12 to a level that aids in extinguishing the arc butlow enough to prevent back sputtering or mousebites. In the presentlypreferred embodiment of the invention, a forward voltage clamping device42 is connected in series with the reverse voltage clamping device 44,however the scope of the invention encompasses connecting a reversevoltage clamping device 44 in parallel with a forward clamping device 42as well as a reverse voltage clamping device 44 with no forward clampingdevice (see FIG. 3A, voltage clamp 32A). In the presently preferredembodiment the reverse voltage clamping device 44 is a unidirectionalzener diode (transorb) in series with the forward voltage clampingdevice 42. Two less preferred implementations are illustrated in FIGS.3A and 3B as voltage clamps 32A and 32B. In voltage clamp 32A, thereverse voltage clamping device 44 is a series of unidirectional zenerdiodes in series with a reverse biased diode. In voltage clamp 32B, thereverse voltage clamping device 44, is a bidirectional zener diode thatis in series with a string of unidirectional zener diodes.

The forward voltage clamping device 42 protects the sputtering system 10from excessive forward output voltages. The selection and implementationof forward voltage clamping devices is well-known to those skilled inthe art. In presently preferred embodiment a series of unidirectionalzener diodes are used as the forward voltage clamping device.

Actual deposition of the coating requires the ignition of a plasmawithin the sputtering chamber 12. The plasma is created by applying avoltage between the anode 20 and the cathode 18 that is sufficientlyhigh to cause ionization of at least a portion of the sputtering gas.The intense electric field associated with the applied voltage stripselectrons from the gas atoms, creating anions and electrons that flowwithin the plasma. The anions are accelerated by the steady-stateelectric field into the target 18 with sufficient kinetic energy tocause the anions to knock atoms from the target 18. Some of the freedtarget atoms combine with atmosphere that is present within thesputtering chamber 12 at the beginning of the process. The remainingfreed target atoms that are uncombined also disperse throughout thesputtering chamber 12 coating the exposed surfaces. Throughout theprocess arcing occurs intermittently due to target poisoning, outgassingfrom the workpiece 16, contaminants, and flakes amongst other causes.

Referring to FIGS. 3 and 5, the operation of the sputtering system 10during an arc will be described. When an arc occurs, the impedance fromcathode 18 to anode 20 dramatically decreases, causing a rapid rise incathode current 48. The increase in cathode current 48 is supplied fromenergy stored in the output capacitor 36 and resonant capacitor 38. Asthe transient current continues to flow, energy stored in the outputcapacitor 36 and resonant capacitor 38 transfers into the resonantinductor 40. The cathode current 48 reaches a peak value when thevoltage across capacitors 36 and 38 resonates to 0. As those skilled inthe art will realize, the peak value of the cathode current 48 isrelated to the ratio of the energy stored in resonant inductor 40 andcapacitors 36 and 38. This ratio is commonly referred to as the Q of thefilter. As the cathode current 48 begins to decrease, energy starts totransfer out of resonant inductor 40 back into capacitors 36 and 38,reverse charging the capacitors. The voltage applied from cathode 18 toanode 20, cathode voltage 50, reverses as charge continues to flow intocapacitors 36 and 38. Thus, resonant inductor 40 and capacitors 36 and38 have a Q such that in reaction to occurrence of an arc, the cathodecurrent 48 resonates to a reverse current level.

The amplitude of the reverse voltage applied to the cathode 18 continuesto increase until the reverse voltage clamping device 42 becomes active.One prior technique allows this voltage to reverse to a nearly equalvalue of the normal cathode voltage, (+500 volts to −500 volts). Anotherprior technique clamps the negative voltage at or about zero volts,allowing no reverse current to flow to the cathode. In the presentlypreferred embodiment, the reverse voltage clamping device 42 ispreferably selected to clamp the cathode 18 to a voltage less than 200V.The present invention recognizes that mousebites are caused bysubstantial reverse power flow through the anode 20. Therefore, formousebites to occur, there must be substantial reverse voltage inaddition to reverse current applied to the cathode 18. Mousebites arecaused by back sputtering from the workpiece when a sufficient reversevoltage and current are applied. In the present embodiment, backsputtering begins to occur at reverse voltage levels of 200 volts orgreater. The mousebites occur at the boundaries of the workpiece becausethese are the locations of the highest electric field intensity, andtherefore the first locations to breakdown the reactive gas and allowreverse current flow. It is within the scope of the invention to selecta clamping voltage for the clamping device 42 that is sufficient toextinguish arcing but is less than the back sputtering voltage that willcause mousebites.

The present invention also recognizes that providing a reverse voltageless than the sputtering voltage during an arc may reduce the recoverytime of the sputtering system 10. The reverse voltage applied to thecathode 18 aids in extinguishing the arc. In the presently preferredembodiment, the sputtering system 10 recovers from an arc within about6μ secs. In addition, less energy is dissipated in the arc since aportion of the energy from the energy storage components is dissipatedwithin the reverse voltage clamping device 42. The quantity ofparticulate defects generated by the arc is reduced since less energy isdissipated within the arc and the duration of the arc is shortened.Also, applying a reverse voltage to the cathode 18 reduces the tendencyfor subsequent arcing during reactive deposition processes by reducingthe charge stored by the parasitic capacitance formed from the targetmaterial and insulator compounds.

After the arc is extinguished, the cathode current continues toresonate. As the cathode current 48 passes through zero amps, thecathode voltage 50 reestablishes the sputtering voltage and power.

Referring to FIGS. 4A, 4B, and 4C, the state of the sputtering system 10during a voltage reversal is contrasted with conventional sputteringsystems. FIG. 4B illustrates the operation of a conventional sputteringsystem during a voltage reversal. FIG. 4C illustrates the operation ofthe presently preferred embodiment of the sputtering system 10 during avoltage reversal. During normal operation, prior to an arc occurring,target material sputtered off from the cathode 18 forms a coating 19 onthe workpiece 16. As the coating 19 is formed, a low-level negativecharge accumulates within the coating 19 as well as along the surface ofthe coating 19. When a voltage reversal occurs, the voltage on thecathode 18 swings positive relative to the anode 20. Positive anionsthat previously were attracted to the cathode 18 are increasinglyrepelled as the reverse voltage increases in magnitude.

In conventional sputtering systems (see FIG. 4B), the positive anionsinstead of flowing towards the cathode 18, increasingly flow towards thenegatively charged workpiece 16. As the anions flow towards theworkpiece 16, they are attracted towards the outer and inner edges ofthe coating 19 due to the high electric fields present in those regions.When the anions strike the coating 19, momentum transfer occurs causingportions of the coating 19 to be back sputtered, with the majority ofthe sputtering occurring along the edges. Mousebites 9 are exhibited asthe back sputtering along the edges of the coating 19 continues. Theback sputtered coating 19 which comprises mainly aluminum with a smallerproportion of Al₂O₃, is deposited on the inner surfaces of thesputtering chamber 12 including the shields 14 and 17, and the cathode18.

In the presently preferred embodiment of the sputtering system 10, themagnitude of the voltage reversal is clamped at a sufficiently lowvoltage to prevent the flow of positive anions towards the negativelycharged workpiece 16. Since anions do not strike the coating 19, themousebites 9 that plagued conventional sputtering systems are preventedfrom occurring in the presently preferred embodiment.

The arc control system of the present invention minimizes the time torecover from an arc, thereby increasing the proportion of process timeduring which deposition of material occurs. Additionally, the systemprevents the formation of mousebites during an arc.

Also, the arc control system decreases the arc energy that is dissipatedin the chamber, thereby reducing defects in the workpiece. In addition,the period of time before subsequent arcs occur is lengthened, againincreasing the process time during which deposition of material occurs.

Further, the arc control system is designed with a comparatively smallnumber of passive components.

Thus it will be appreciated from the above that as a result of thepresent invention, an arc control method for DC sputtering systems isprovided by which the principal objectives, among others, are completelyfulfilled. It will be equally apparent and is contemplated thatmodification and/or changes may be made in the illustrated embodimentwithout departure from the invention. Accordingly, it is expresslyintended that the foregoing description and accompanying drawings areillustrative of preferred embodiments only, not limiting, and that thetrue spirit and scope of the present invention will be determined byreference to the appended claims and their legal equivalent.

What is claimed is:
 1. An arc control system for responding to an arc in a DC sputtering system, comprising: a sputtering chamber that houses an anode and a sputtering target formed from a target material and serving as a cathode; a DC power supply configured to provide a direct current cathode voltage such that a cathode current flows through the anode and the cathode, the DC power supply having an output filter that includes an output inductor and an output capacitor; a first circuit branch coupled across the DC power supply, the first circuit branch comprising a resonant capacitor; and a second circuit branch coupled across the DC power supply in parallel with the first circuit branch, the second circuit branch comprising a resonant inductor in series with a parallel combination of a first circuit subbranch and a second circuit subbranch, wherein the first circuit subbranch comprises the sputtering chamber and the second circuit subbranch comprises a reverse voltage clamp; and further wherein the resonant capacitor and the resonant inductor comprise a resonant network configured to provide a Q such that in reaction to the occurrence of an arc, the cathode current resonates to a reverse current level and wherein the reverse voltage clamp is configured to clamp the cathode voltage to a predetermined clamp voltage.
 2. The arc control system of claim 1 wherein the reverse voltage clamp comprises at least one zener diode in series with a reverse biased diode.
 3. The arc control system of claim 1 further comprising a forward voltage clamp in series with the reverse voltage clamp, wherein the reverse voltage clamp comprises at least one bi-directional zener diode and the forward voltage clamp comprises at least one unidirectional zener diode.
 4. The arc control system of claim 1 wherein the DC power supply is selected from the group of: SCR power supplies, switchmode power supplies, and diode-transformer power supplies.
 5. The arc control system of claim 1 wherein the predetermined clamp voltage is less than a backsputtering voltage.
 6. The arc control system of claim 1 wherein the DC sputtering system is a DC reactive sputtering system.
 7. The arc control system of claim 6 wherein the target material is selected from the group of: aluminum, silicon, titanium, tantalum, zircon, carbon, and boron.
 8. The arc control system of claim 6 wherein the target material is selected from the group of metallic materials and metallic compounds.
 9. An arc control system for responding to an arc in a DC sputtering system, comprising: a sputtering chamber that houses an anode and a sputtering target formed from a target material and serving as a cathode, the target material being formed from a metallic material; a DC power supply configured to provide a direct current cathode voltage such that a cathode current flows through the anode and the cathode, the DC power supply having an output filter that includes an output inductor and an output capacitor; a first circuit branch coupled across the DC power supply, the first circuit branch including a resonant capacitor; and a second circuit branch coupled across the DC power supply in parallel with the first circuit branch, the second circuit branch comprising a resonant inductor in series with a parallel combination of a first circuit subbranch and a second circuit subbranch, wherein the first circuit subbranch comprises the sputtering chamber and the second circuit subbranch comprises a series connected bidirectional zener diode and a unidirectional zener diode; and further wherein the resonant capacitor and the resonant inductor comprise a resonant network configured to provide a Q such that in reaction to the occurrence of an arc, the cathode current resonates to a negative current, and wherein the series connected bidirectional zener diode and the unidirectional zener diode are configured to clamp the cathode voltage to a predetermined reverse voltage when the cathode current resonates to the negative current.
 10. The arc control system of claim 9 wherein the DC power supply provides a forward voltage of approximately in the range of 200 volts to 800 volts and the predetermined reverse voltage is in the range of about 75 volts to 200 volts.
 11. An arc control system for responding to an arc in a DC sputtering system, comprising: a sputtering chamber that houses an anode and a sputtering target formed from a target material and serving as a cathode, a DC power supply configured to provide a direct current cathode voltage such that a cathode current flows through the anode and the cathode; a first circuit branch coupled across the DC power supply, the first circuit branch including a resonant capacitor; a second circuit branch coupled across the DC power supply in parallel with the first circuit branch, the second circuit branch comprising a resonant inductor in series with a parallel combination of a first circuit subbranch and a second circuit subbranch, wherein the first circuit subbranch comprises the sputtering chamber and the second circuit subbranch comprises a reverse voltage clamp; and further wherein the resonant capacitor and the resonant inductor comprise a resonant network separate from the DC power supply and configured to provide a Q such that in reaction to the occurrence of an arc, the cathode current resonates to a reverse current level and wherein the reverse voltage clamp is configured to clamp the cathode voltage to a predetermined clamp voltage.
 12. The arc control system of claim 11 wherein the reverse voltage clamp comprises at least one zener diode in series with a reverse biased diode.
 13. The arc control system of claim 11 further comprising a forward voltage clamp in series with the reverse voltage clamp, wherein the reverse voltage clamp comprises at least one bi-directional zener diode and the forward voltage clamp comprises at least one unidirectional zener diode.
 14. The arc control system of claim 11 wherein the DC power supply is selected from the group of: SCR power supplies, switchmode power supplies, and diode-transformer power supplies.
 15. The arc control system of claim 11 wherein the predetermined clamp voltage is less than a backsputtering voltage.
 16. The arc control system of claim 11 wherein the DC sputtering system is a DC reactive sputtering system.
 17. The arc control system of claim 16 wherein the target material is selected form the group consisting of: metallic materials, metallic compounds, aluminum, silicon, titanium, tantalum, zircon, carbon, and boron.
 18. The arc control system of claim 16 wherein the target material is selected from the group consisting of metallic materials and metallic compounds.
 19. An arc control system for responding to an arc in a DC sputtering system, comprising: a sputtering chamber that houses an anode and a sputtering target formed from a target material and serving as a cathode, a DC power supply configured to provide a direct current cathode voltage such that a cathode current flows through the anode and the cathode; a first circuit branch coupled across the DC power supply, the first circuit branch including a resonant capacitor; a second circuit branch coupled across the DC power supply in parallel with the first circuit branch, the second circuit branch comprising a resonant inductor in series with a parallel combination of a first circuit subbranch and a second circuit subbranch, wherein the first circuit subbranch comprises the sputtering chamber and the second circuit subbranch comprises a series connected bidirectional zener diode and a unidirectional zener diode; and further wherein the resonant capacitor and the resonant inductor comprise a resonant network separate from the DC power supply and configured to provide a Q such that in reaction to the occurrence of an arc, the cathode current resonates to a negative current, and wherein the series connected bi-directional zener diode and the unidirectional zener diode are configured to clamp the cathode voltage to a predetermined reverse voltage when the cathode current resonates to the negative current.
 20. The arc control system of claim 19 wherein the DC power supply provides a forward voltage of approximately in the range of 200 volts to 800 volts and the predetermined reverse voltage is in the range of about 75 volts to 200 volts. 